Method for activating recordings of events concerning terminals and equipment thereof

ABSTRACT

The invention concerns a method which consists, in a radio communication system comprising a core network, at least one radio network controller connected to the core network and configured to control radio communications with terminals and at least one operation center capable of supervising said radio network controller, in: transmitting from the operating center to a radio network controller, a coded list of terminal identifiers; transmitting the coded list to the control network from the radio network controller; decoding the coded list at the core network; detecting at the core network a radio communication under the control of the radio network controller, with a terminal identified in the decoded list; and instructing the radio network controller, from the core network, to start a recording of events concerning the detected communication.

This is the U.S. National Phase of International Application No.PCT/FR2004/001095 filed 6 May 2004, the entire disclosure of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to recordings of events concerning theterminals in a radiocommunication system. It relates more particularlyto the method of activating such recordings.

The recording of certain events that can occur in a call or an exchangeof information with a terminal is a routine operation inradiocommunication systems. The duly stored events are normallysignaling messages, typically of level 3, interchanged between theterminal and the radiocommunication system. Such an operation is knownby the term “trace”.

The trace is performed on one or more nodes of the radiocommunicationsystem and can be used by the operator of this system for subsequentprocessing purposes (statistical analysis of calls in a geographic area,study of the behavior of a particular call, etc).

It has, for example, been the subject of standardization in the GSM(Global System for Mobile communications) system, in the technicalspecification TS 100 627 or GSM 12.08, version 4.6.1, “Subscriber andequipment trace”, published in October 2001 by the ETSI (EuropeanTelecommunications Standards Institute).

In the UMTS (Universal Mobile Telecommunication System) system, it isprovided for the trace to be able to be implemented in the radio part ofthe universal terrestrial radio access network (UTRAN) to recordsignaling elements on the Iu interfaces (between a switch of the corenetwork and a radio network controller), Iur interfaces (between tworadio network controllers), Iub interfaces (between a radio networkcontroller and a base station) and radio interfaces (between a radionetwork controller and a radio terminal).

The activation of the trace involves transmitting an instruction to thenode which will carry out the recording. This activation is normallybased on the identifier of a terminal for which calls need to be thesubject of a trace. The identifier of the terminal can relate to thesubscriber using the terminal. In this case, the identifier willadvantageously be the conventional IMSI (International Mobile StationIdentity) parameter. It may also relate to the terminal equipment. Inthis case, the identifier will, for example, be the conventional IMEI(International Mobile station Equipment Identity) parameter, a parameterobtained from the IMEI, or even the IMEISV (IMEI Software Version)parameter.

When the trace needs to be performed by a radio network controller in asystem such as UMTS, that is, in an RNC (Radio Network Controller), twomodes of activation are possible.

In a first mode, the trace is activated by the transmission of aninstruction to the RNC from the core network. It is typically the HLR(Home Location Register), which is a database of the core networkcontaining information relating to the subscribers of the network, whichthen originates the instruction, which will be transmitted to the RNCvia the Iu interface. This mode of activation of the trace by signaling(signaling activation) is particularly suitable for performing a traceon calls from a particular subscriber of the network.

In a second mode, the trace is activated locally on the RNC. Thisactivation is normally performed via an operation and maintenancecenter, for example, the OMC in UMTS which transmits the instruction tothe RNC concerned. This mode of activation of the trace (managementactivation) is well suited in particular to the cases where there is adesire for recordings on a given area of the network, possibly for aparticular type of equipment.

The second mode of activation is widely used in practice, particularlyin the GSM system, because it is simple to implement and also providesoperators with relevant statistics, for example concerning the behaviorof a terminal model in a targeted geographic area of their network.

Transposing this functionality to the UMTS system would entailtransmitting a terminal identifier to the RNC. Now, the main players inthe field concerned consider the systematic presence of such anidentifier within the RNC to be totally undesirable for various reasons.

Furthermore, when the terminal identifier used is an equipment identity,for example the IMEI, a trace activation at the RNC based on thisparameter would require the RNC to be able to know the IMEI of eachterminal involved in a call under its control. Normally, when an IMEI istransmitted by a terminal to the core network, it is done sotransparently for the RNC. The RNC can therefore have the IMEI parameteronly if the core network sends it to it specifically. Such a mechanismwould then result in a signaling overload prejudicial to the system.

One object of the present invention is to overcome the abovementioneddrawbacks, by proposing an effective mechanism for activating the trace.

SUMMARY OF THE INVENTION

The invention thus proposes a method of activating recordings of eventsconcerning radio terminals in a radiocommunication system including acore network, at least one radio network controller connected to thecore network and designed to control radio communications with terminalsand at least one operation center suitable for supervising said radionetwork controller, the method including the following steps:

-   -   transmitting, from the operation center to a radio network        controller, a coded list of terminal identifiers;    -   transmitting the coded list of terminal identifiers to the core        network from the radio network controller;    -   decoding the coded list of terminal identifiers at the core        network;    -   detecting, at the core network, a radio communication under the        control of the radio network controller, with a terminal        identified from the decoded list; and    -   instructing the radio network controller, from the core network,        to start a recording of events relating to the detected call.

Such a mode of operation ensures the flexibility of a local activationof the trace, via the operation center, which may be an OMC, or even asupervisory unit co-located with a radio network controller. It alsoenables the management of the trace activation instruction to be left tothe core network. Furthermore, it allows for local activation of thetrace in the radio network controller while avoiding systematicallyproviding the latter with the terminal identifier for each call.

The invention also proposes a radiocommunication system designed toimplement the method of activating the abovementioned trace.

It further proposes an operation center, a core network and a radionetwork controller suitable for contributing to the implementation ofthe method.

BRIEF DESCRIPTION OF THE DRAWINGS

The single FIGURE is a simplified diagram of a system suitable forimplementing the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

The FIGURE shows a radiocommunication system including RNCs 1, a corenetwork CN 2 and an OMC 3, in accordance with the normal definitions ofthese component elements of a UMTS network summarized in theintroduction.

The CN 2 includes a meshed arrangement of switches suitable fortransmitting speech traffic in circuit mode such as the MSC (Mobileservice Switching Center) 8 or data traffic in packet mode such as theSGSN (Serving GPRS Support Node) 6, GPRS standing for “General PacketRadio Service”. The switches are conventionally linked to each otherand/or to a particular switch used as a platform towards an externalnetwork, such as, for example, the GGSN (Gateway GPRS Support Node) 7which is interconnected with an IP (Internet Protocol) type data network10 in the example illustrated in the FIGURE.

The RNCs 1 are linked to the CN 2, via a switch of the CN, for examplean SGSN 6 or an MSC 8. The standardized interface that links theseelements is the Iu interface.

Moreover, the OMC 3 is capable of supervising and operating the RNCs 1,via the interface that links it to these elements. The OMC is aconventional operation and maintenance entity in the systems of the typeof that in the FIGURE. However, other elements could also be used tosupervise the system. The latter can be grouped under the genericfunctional designation of OSS (Operations Support System).

An RNC 1 has under its control a set of base stations 5 or nodes Baccording to the UMTS terminology, via which radio terminals 4 cancommunicate with the RNC.

According to the invention, when there is a desire to activate tracesrelating to terminals, for current or future calls, a request must besent to the RNC 1 controlling these calls. For this, the request can betransmitted via the OMC 3, as in the case of a “management” typeactivation. This request is then transferred to the or each RNC 1 towhich it is addressed, via the interface linking these entities. It isworth noting that the activation request could also be sent direct tothe RNC 1 concerned or via a physical unit co-located with the RNC 1.However, a centralized operation unit for sending this request offersgreater flexibility of implementation.

The trace activation request advantageously includes parameters relatingto trace implementation procedures. For example, these parameters mayspecify a recording duration to be observed, or even a list identifyingbase stations under the control of the RNC 1 within the coverage area ofwhich the calls must be the subject of a trace.

The trace activation request is generic inasmuch as it does not specifya particular terminal identifier (so as to avoid the risks stated in theintroduction), but includes a coded list of terminal identifiers.

As indicated above, the term “terminal identifier” is understood to meanan identifier designating a subscriber or even an element. The lattercase is assumed below.

The terminal identifier may be the IMEI, as is specified in the ETSItechnical specification TS 123 003, version 5.5.1, Release 5,“Numbering, Addressing and Identification” (3GPP TS 23.003), publishedby the 3GPP (3rd Generation Partnership Project) in January 2003. It isalso possible to use other parameters to identify the terminal. Forexample, the IMEISV can be used when it is available in the system used.This complements the IMEI with a software version (SV) number inaccordance with the abovementioned technical specification 122 016.Naturally, any other relevant parameter may be used in this context. Theterm IMEI will be used hereinafter, without prejudicing the fact thatthe terminal identifier used may be different.

The generic trace activation request therefore includes a coded list ofIMEIs for respective terminals. For example, the coding used may be anIMEI “mask”, that is, a specification of the value of only certain bitsof the IMEI, the unspecified bits being of any possible values.

Thus, the IMEI value for which a trace must be implemented is notcommunicated as such to the RNC in the generic trace activation request.

Advantageously, the RNC 1 having received the trace activation requestdetermines a reference that it associates with the request, that is,with the coded list of IMEIs. This reference can subsequently be used toidentify the traces made in relation to said activation request.

The RNC 1 then transmits, to a node of the CN 2, for example an MSC 8 oran SGSN 6, the coded list of IMEIs that it has received. Thistransmission is carried out without the RNC having previously decodedthe coded list of IMEIs and preferably without it retaining a copy ofit. This ensures that the IMEIs included in the coded list will not beknown individually to the RNC 1. Advantageously, this transmissioncontains the corresponding reference determined by the RNC 1.

A distinction is therefore made from the “management” type traceactivation, since the RNC does not implement the trace at this stage,inasmuch as it has not identified the IMEIs that must be the subject ofa trace.

The node having received the coded list of IMEIs from the RNC 1, forexample the SGSN 6, then decodes this list. It then checks, each time acall is set up or information is interchanged with a terminal within thearea under the control of the RNC 1, whether the terminal has an IMEIbelonging to the coded list of IMEIs. When the coding used is a mask,the SGSN 6 checks whether this mask applies to the IMEI of the terminalengaged in the call, that is, whether the IMEI of this terminal has theformat specified by the mask. If it does, this means that the callinvolving this terminal must be the subject of a trace.

If the SGSN 6 has detected a call that must be the subject of a trace,it then instructs the activation of such a trace at the RNC 1, in thesame way as it would have done if the “signaling” activation mode hadbeen implemented in the system represented in the FIGURE.

Advantageously, the activation instruction sent from the SGSN 6 to theRNC 1 contains the reference previously determined by the RNC 1. Thetransmission of this reference makes it possible to establish the linkbetween the trace activation request initially formulated by the OMC 3,that is, the initial transmission of the coded list of IMEIs, and thetrace finally implemented at the RNC 1.

The trace activation instruction can be sent via a new signaling messageor even an existing message between the CN 2 and the RNC 1. In thelatter case, the message “CN Invoke Trace” specified in section 8.17 ofthe technical specification 25.413, version 5.4.0, Release 5, “UTRAN Iuinterface RANAP signaling”, published by the 3GPP in March 2003, canadvantageously be used.

This part of the trace activation mechanism is similar to the“signaling” activation. The trace activation instruction transmitted bythe CN 2 identifies the call that must be the subject of a trace, forexample, by indicating to the RNC 1 an identifier of the correspondingconnection.

On receipt of the trace activation instruction, the RNC 1 is thereforeable to start the recording of events for the detected call, as it wouldhave done in the case of a “signaling” type activation. Furthermore,when the activation message received from the CN 2 includes thereference previously determined for the initial trace request, the RNC 1finds the parameters relating to the trace implementation proceduresthat had been transmitted to it initially by the OMC 3, and it linksthem to the trace that it is about to start.

It is worth noting that the activation instruction can itself containother information relating to recording procedures that will berecognized by the RNC 1, for example a designation of the type of traceto be performed. The type of trace then gives indications on traceimplementation procedures, for example on the events to be recorded. Theactivation instruction can also contain the identity of an OMC to whichthe trace will be sent, once completed, for subsequent analysis andprocessing purposes. The message “CN Invoke Trace” described abovemoreover provides fields for this purpose.

With the invention disclosed above, the trace activation therefore hasthe simplicity of implementation of the “management” mode since theinitial trace request is made locally, possibly via an OMC. It alsoavoids the drawbacks associated with this trace activation mode and inparticular the need for the RNC concerned to know and check the identityof each terminal in its control area. This latter point is handled bythe intervention of the CN which ultimately instructs the activation ofthe trace when it detects a call or an information interchange involvinga terminal that is part of the group of terminals to be traced,according to a procedure similar to the “signaling” activation mode.

1. A method of activating recordings of events concerning radioterminals in a radiocommunication system including a core network, atleast one radio network controller connected to the core network anddesigned to control radio communications with terminals and at least oneoperation center suitable for supervising said radio network controller,the method including the following steps: transmitting, from theoperation center to a radio network controller, a coded list of terminalidentifiers; transmitting the coded list of terminal identifiers to thecore network from the radio network controller; decoding the coded listof terminal identifiers at the core network; detecting, at the corenetwork, a radio communication under the control of the radio networkcontroller, with a terminal identified from the decoded list; andinstructing the radio network controller, from the core network, tostart a recording of events relating to the detected call.
 2. The methodas claimed in claim 1, wherein the transmission of the coded list ofterminal identifiers also includes the transmission of a set ofparameters relating to recording procedures including a recordingduration or identifiers of areas under the control of the radio networkcontroller to which the recordings of events are limited, and in whichthe recording of events relating to the detected call conforms to saidrecording procedures.
 3. The method as claimed in claim 1, wherein areference is allocated by the radio network controller to the coded listof terminal identifiers, and wherein said reference is transmitted tothe core network in conjunction with the coded list of terminalidentifiers.
 4. The method as claimed in claim 3, wherein theinstruction to start a recording of events concerning the detected callalso includes the reference allocated to the coded list of terminalidentifiers.
 5. The method as claimed in claim 1, wherein theinstruction to start a recording of events concerning the detected callalso includes an indication concerning recording procedures including anidentification of the events that must be the subject of the recording.6. An operation center in a radiocommunication system designed toimplement an activation of recordings of events concerning radioterminals, the radiocommunication system also including a core network,at least one radio network controller connected to the core network anddesigned to control radio communications with terminals, the operationcenter including means for supervising said radio network controller andmeans for transmitting a coded list of terminal identifiers to the radionetwork controller; wherein the means for transmitting a coded list ofterminal identifiers to the radio network controller include means foralso transmitting a set of parameters relating to recording proceduresincluding a recording duration or identifiers of areas under the controlof the radio network controller to which the recordings of events arelimited; the radio network controller comprising: means for transmittingthe coded list of terminal identifiers to the core network; means forapplying the set of parameters as an instruction to start a recording ofevents concerning a call with a terminal identified from the coded listof terminal identifiers, said call having been detected in the corenetwork; means for allocating a reference to the coded list of terminalidentifiers; and means for transmitting said reference to the corenetwork in conjunction with the coded list of terminal identifiers;wherein the means for applying also apply the set of parameters as anidentification of the events that must be the subject of the recording.7. A radio network controller in a radiocommunication system designed toimplement an activation of recordings of events concerning radioterminals, the radiocommunication system also including a core networkand an operation center suitable for supervising the radio networkcontroller, the radio network controller being connected to the corenetwork and including means for controlling radio communications withterminals and also including: means for receiving from the operationcenter a coded list of terminal identifiers; means for transmitting thecoded list of terminal identifiers to the core network; means forreceiving, from the core network, and applying an instruction to start arecording of events concerning a call with a terminal identified fromthe coded list of terminal identifiers, said call having been detectedin the core network; means for allocating a reference to the coded listof terminal identifiers: and means for transmitting said reference tothe core network in conjunction with the coded list of terminalidentifiers; wherein the means for receiving an instruction to start arecording of events concerning a call include means for also receivingan indication relating to recording procedures including anidentification of the events that must be the subject of the recording.8. The radio network controller as claimed in claim 7, wherein the meansfor receiving a coded list of terminal identifiers include means foralso receiving a set of parameters relating to recording proceduresincluding a recording duration or identifiers of areas under the controlof the radio network controller to which the recordings of events arelimited, the radio network controller also including means for applyingthe instruction to start the recording of events concerning said call insuch a way that said call complies with said recording procedures. 9.The radio network controller as claimed claim 7, wherein the means forreceiving an instruction to start a recording of events concerning acall include means for also receiving the reference allocated to thecoded list of terminal identifiers.
 10. A core network of aradiocommunication system designed to implement an activation ofrecording of events concerning radio terminals, the radiocommunicationsystem also including at least one radio network controller connected tothe core network and designed to control radio communications with radioterminals and at least one operation center suitable for supervisingsaid radio network controller, the core network including: means forreceiving, from the radio network controller, a coded list of terminalidentifiers; means for decoding the coded list; means for detecting acall under the control of the radio network controller, with a terminalidentified from the decoded list; means for instructing the radionetwork controller to start a recording of events concerning thedetected call; and means for receiving a reference in conjunction withthe coded list.
 11. The core network as claimed in claim 10, wherein themeans for instructing the start of a recording of events concerning thedetected call include means for transmitting said reference.
 12. Thecore network as claimed in claim 10, wherein the means for instructingthe start of a recording of events concerning the detected call includemeans for transmitting an indication relating to recording proceduresincluding an identification of the events that must be the subject ofthe recording.
 13. A radiocommunication system including a core network,at least one radio network controller connected to the core network anddesigned to control radio communications with terminals and at least oneoperation center suitable for supervising said radio network controller,the radiocommunication system comprising: means for transmitting, fromthe operation center to a radio network controller, a coded list ofterminal identifiers; means for transmitting the coded list of terminalidentifiers to the core network from the radio network controller; meansfor decoding the coded list of terminal identifiers at the core network;means for detecting, at the core network, a radio communication underthe control of the radio network controller, with a terminal identifiedfrom the decoded list; and means for instructing the radio networkcontroller, from the core network, to start a recording of eventsrelating to the detected call.
 14. A radiocommunication system asclaimed in claim 13, wherein the means for transmitting the coded listof terminal identifiers include means for transmitting a set ofparameters relating to recording procedures including a recordingduration or identifiers of areas under the control of the radio networkcontroller to which the recordings of events are limited, and in whichthe recording of events relating to the detected call conforms to saidrecording procedures.
 15. A radiocommunication system as claimed inclaim 13, comprising means for allocating a reference to the coded listof terminal identifiers by the radio network controller, and means fortransmitting said reference to the core network in conjunction with thecoded list of terminal identifiers.
 16. A radiocommunication system asclaimed in claim 15, wherein the instruction to start a recording ofevents concerning the detected call also includes the referenceallocated to the coded list of terminal identifiers.
 17. Aradiocommunication system as claimed in claim 13, wherein theinstruction to start a recording of events concerning the detected callalso includes an indication concerning recording procedures including anidentification of the events that must be the subject of the recording.